The commit 76cfc9405ea8b318e8b1c589fa245f86a5827b71 moved all quota_*
options to the separate quota section but the commit missed one usage
of the old quota_driver option, and the remaining usage causes
the following warning warning to appear repeatedly.
Config option None.quota_driver is deprecated.
Use option quota.driver instead.
This replaces the remaining usage to get rid of that warning.
Related-Bug: #1934025
Closes-Bug: #1983125
Change-Id: Ie49dbe4633a34d1832f0dedb658d83ec74d351df
68a5e93ff9